When you don't listen well when a friend of yours is talking, it can be annoying. But it is more than that. Your poor listening has real consequences in your friend's life.
Your friend will not be able to solve his or her problems as well, it can raise his or her level of stress, and much more.
Read about it here: Consequences of Not Listening Well.
Here's what it means to be a good listener: How to Listen in a Way That Helps.